Conveyors systems are utilized in many industries, typically including the manufacturing and packaging industries. These conveyor systems can be of many types, such as continuous belt conveyors, shaker (inertial) conveyors, etc. Often the articles being transported must be deposited upon further conveyor units as in the case of a change in direction of the transfer. In the case of the continuous belt type conveyor, when articles are to be deposited upon another belt there is often a drop of several inches due to the size of the rollers/wheels that carry the belt. For some types of articles that are fragile, such as foodstuffs, this drop is detrimental. In the case of the shaker- or inertial-type conveyors, very little drop distance can be provided such that there is no damage to the articles being transferred. Also, the tray in this latter type of conveyor can be made of materials that will not be damaged by the material being transferred and, more importantly, will not contaminate the materials being transferred.
A problem that has been encountered in the prior art is the matter of the vibration that often occurs with the devices for inertial-type conveyors. The principle of these conveyors is to cause vibration of the transfer tray such that during a "forward" stroke, the articles are moved with the tray. Then, during the "return" stroke, the inertia of the articles causes them to remain in motion slipping along the tray as the tray is returned. To accomplish this, the tray oscillation is produced by a wide number of mechanisms. Some of these create substantial vibration such that the machine must be firmly attached to a support surface.
A number of mechanisms have been devised to produce the tray oscillation and, in some of the designs, to minimize the vibration. Typically of these prior art devices are those shown and described in U.S. Pat. Nos. 218,757 issued to F. Martin, Jr. on Aug. 19, 1879; 1,843,282 issued to E. Horn et al on Feb. 2, 1932; 3,212,630 issued to K. M. Allen et al on Oct. 19, 1965; 4,019,626 issued to H. J. Kamner on Apr. 26, 1977; and 4,339,029 issued to D. A. Wilson On Jul 13, 1982.
Still other references that may be material relative to the present invention are U.S. Pat. Nos.: 3,476,234 issued to K. L, M. Allen, et al on Nov. 4, 1969; 3,817,370 issued to J. P. Cox on Jun. 18, 1974; 4,436,199 issued to K. Baba, et al on Mar. 13, 1984; and 4,567,979 issued to R. A. Hoehn on Feb. 4, 1986. In particular, the '234 Allen reference uses two conveyor members that are driven longitudinally by a single drive means, with one conveyor member used to counter the vibration of the other. As each conveyor moves in a first direction, it is moved downwardly; then, as it is moved in the opposite direction, it is moved upwardly to advance any material supported thereon. The structure provides a generally back-and-forth vibratory motion, with a tossing motion being given to the conveyors and thus to the material. Both conveyor members have the same acceleration in each direction of motion as they are driven by a common crankshaft-eccentric mechanism.
All of these known systems must be designed for the transport of a specific article on the conveyor, with the exception of those described in the '626 and '019 patents which can be modified for specific products. However, even with the effort to minimize vibration, each of these devices does produce undesirable vibration (and thus noise) during operation. Further, some of these systems (e.g., the '234 reference) will damage fragile items being transported on the tray thereof. While these patents describe the principles of inertial conveyance, several are constructed without an understanding of these principles.
Accordingly, it is an object of the present invention to provide an inertial-type convey system that substantially eliminates vibration effects of the operating mechanism.
Another object of the present invention is to provide means for offsetting a reaction force produced by the acceleration of the conveyor tray and for offsetting a couple produced by that reaction force to thereby eliminate vibrational effects.
It is another object of the present invention to provide an inertial conveyor system utilizing a counterbalance (counterweight) means to offset the reaction force produced by the moving of the conveyor tray means so as to substantially eliminate vibration effects of the operating mechanism.
It is also an object of the present invention to provide a conveyor system using a counterweight means to overcome vibration where the weight of the counterweight means is substantially equal to the weight of the conveyor tray means and wherein the center of mass of the counterweight means is matched to the center of mass of the conveyor tray means along a common line of action in order so as to provide for offsetting the reaction force and the couple produced by the acceleration of the conveyor tray means.
These and other objects of the present invention will become apparent upon a consideration of the drawings which are referenced below and a complete description thereof.